• Journal of Mechanical Science and Technology
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• 제14권12호
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• pp.1376-1385
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• 2000

This study investigates spray characteristics before and after wall impingingment of gasoline spray in suction air flow. For this study, a rectangular model intake port was made of acrylic glass, and suction air was generated by using the forced air blower contrariwise. The injector for this study was a pintle-type port gasoline injector in which an air-assist adaptor is installed to supply assisted air. A PDPA system was employed to simultaneously measure the size and velocity of droplets near the wall. Measured droplets are divided into "pre-impinging droplets"with positive normal velocity and "post-impinging droplets"were negative normal velocity for the suction flow. The velocities, size distributions and Sauter mean diameter(SMD) of pre-and post-impinging droplets for varions injection angles and air-assists are comparatively analyzed.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.167-173
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• 2003

An experimental study on the behavior of droplets impinging on a solid flat surface was carried out in the present study. Breakup of a liquid droplet impinging on a solid surface has been investigated experimentally for various fuels with different properties. The fuel temperature and incident angle were chosen as major parameters. And fuel temperature and incident angle varied in the range from $-20^{\circ}C$ to $30^{\circ}C$ and from $30^{\circ}$ to $60^{\circ}$, respectively, were investigated. It was found that the variation of fuel temperature influences upon droplet mean diameter which were bounced out from the solid surface. As the increases of incident angle, the break-out mass flow rate increases. This causes the decrease of liquid film flow rate. The larger incident angle gives less liquid film flow rate.

• 대한기계학회논문집
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• 제19권10호
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• pp.2690-2698
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• 1995

Fuel atomization and mixture formation in an gasoline engine has influence on the engine performance and pollutant emission. The throttle valve installed in an intake system plays a greater role in control of mixture quantity in accordance with engine drive condition. In this study, the characteristics of secondary atomization developed at the downstream of the valves were observed using an image processing method. Two major kinds of valves, solid and perforated ones, are chosen in order to compare the valve performance with the experimental parameters of air flow rate, valve opening angle, and valve shapes. For the perforated valve, we can obtain the relatively small sized droplets, and nearly uniformed and dense distributed sprays with low loss coefficient than for the solid valve.

• 한국분무공학회지
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• 제7권3호
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• pp.18-23
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• 2002

An evaporating diesel spray of a common rail lnjector was visualized by LIEF technique. This technique makes it possible to separate the vapor and liquid phase images. The experiment was conducted in a constant volume vessel to make a high temperature and high pressure condition. Three images(vapor and liquid phase images from LIEF and a liquid phase image from Mie scattering) were taken simultaneously in one spray event. The major experimental parameters are the injection pressure and the ambient gas pressure. Also, a relative SMD distribution in a liquid phase was obtained by the ratio of the intensities of the fluorescence and the Mie scattering. The results show that the injection pressure and the ambient gas pressure have a close relation with the spray development and air-fuel muting process.

• 한국분무공학회지
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• 제2권3호
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• pp.25-31
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• 1997

This experiment was undertaken to investigate the spray characteristics of the conventional injection system and the ultrasonic energy added injection system. Test fuels include light oil and mixed light-BC oil. The mixed light-BC oil was injected at the normal temperature$(20^{\circ}C)$ and the high temperature$(95{\pm}2^{\circ}C)$ and injection pressure was $120kg/cm^2$. Sauter mean diameter was measured under the variation of the spray distance. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. It is also found that the condition of the ultrasonic energy added injection and high temperature injection generates the smaller droplets than that of the conventional injection.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.54-60
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• 2008

The atomization characteristics of the dual air supplying twin-fluid nozzle were investigated experimentally using PIV and PDA systems. The two-fluid nozzle is composed of three main parts: the feeding injector to supply fluid that is controlled by a PWM (pulse-width modulation) mode, the adaptor as a device with the ports for supplying the carrier and assist air and the main nozzle to produce the spray. The main nozzle has the swirl tip with four equally spaced tangential slots, which give the injecting fluid an angular momentum. The angle of the swirl tip varied with 0$^{\circ}$ 30$^{\circ}$, 60$^{\circ}$ and 90$^{\circ}$, and the ratios of carrier air to assist air and ALR(total air to liquid) were 0.55 and 1.23, respectively. The macroscopic behavior of the spray was investigated using PIV system, and the mean velocity, turbulent intensity and SMD distributions of the sprays were measured using PDA system. As the results, the mean axial velocity at the spray centerline decrease with the increase of the swirl angle. The turbulent intensities of the axial and radial velocity were increased with the increase of the swirl angle. The mean SMD (Sauter mean diameter) of the radial direction along the axial distance shows the lowest value at the swirl angle of 60$^{\circ}$.

• 한국분무공학회지
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• 제5권3호
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• pp.27-36
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• 2000

In this study, spray characteristics of a dual airblast atomizer are addressed. Three dimensional characteristics of a dual airblast atomizer with air swirl are measured to provide the significant data. The liquid flow rate was fixed at 0.06 kg/min, and atomizing air was controlled at the liquid-air mass ratio of 4.0. The performance of the spray with co-swirl and counter-swirl flow was investigated at each point in the developed spray region using a three-component phase Doppler particle analyzer. This instrument was also used to evaluate the concentration profiles. The three dimensional mean velocity were investigated of present flow characteristics of the dual airblast atomizer. In addition, drop size distributions, mean droplet size profile, and droplet concentration were analyzed to understand atomization characteristics. This experimental results can be conveniently utilized for the preliminary design of gas turbine engines for aircraft.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2721-2730
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• 1996

The present study conducted experimental study of spray combustion to investigate the effect of the inlet conditions of fuel and air on the flame structure, the flame stability and the characteristics of emission in the can-type model of a gas turbine combustor. In the experiment, the diameter of fuel droplet was measured using Malvern particle size analyser and temperatures in the combustion chamber were measured with R-type shielded thermocouple. In addition, flame structure was taken picture with camera and analysed. Gas analyser was also used to analyse the concentration of each components of exhausting gas. The experimental results showed that the flame condition was optimal with swirl number, 0.63 and equivalence ratio, 0.5 for controlling the flame stability, the combustion temperature and the NOx concentration. The present study concluded that both the flame structure and the emission formation were strongly affected by the swirl intensity, which selection was found as an important parameter for either stabilizing flame or lowering the quantity of NOx.

• 한국분무공학회지
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• 제5권1호
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• pp.5-12
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• 2000

The beneficial aspects of applying emulsion fuels to combustion systems may be due to the changes of fuel properties which lead to the enhanced atomization characteristics. The spray characteristics of water/oil emulsified fuel injected from the pressure-swirl(simplex) atomizer using for oil burner were investigated. Four different water contents from 10 to 40 % by volume at 10% increment were prepared by mixing with the different contents of surfactants. Total amount of surfactant used was varied from 1 to 3 % by volume. This study demonstrates the influence of water and surfactant contents of emulsified fuel, injection pressure on the spray characteristics, i.e. Sauter mean diameter(SMD) and spray angle. The drop size distribution of the emulsified fuel spray was measured with a Malvem particle sizer. In order to measure the spray angle, the digital image processing was employed by capturing multiple images of the spray with 3-CCD digital video camera. It was evident that the addition of water and surfactant changes fuel properties which are the key parameters influencing the atomization of the spray. The increase in surfactant content results in the decrease of SMD and the increase in spray angle. The droplets decease with increase in injection pressure, but the influence of injection pressure in this experimental condition was less important than expected. The more viscous fuel with the increase of water content exhibits the larger droplets in the centerline of the spray, and the less viscous fuel in the outer edges of the spray. The increase in axial position from the nozzle causes the spray angle to decrease. The spray angle decreases with increase in water content. This is due to increase in viscosity with increase in water content.

• International Journal of Automotive Technology
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• 제2권4호
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• pp.165-170
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• 2001

This study is focussed on the investigation of spray characteristics from the high pressure gasoline injector for the application of gasoline direct injection engine. For the analysis of spray structure of high pressure gasoline injector; the laser scattering method with a Nd-Yag laser and the Phase Doppler particle analyzer system were applied to observe the spray development and the measurement of the droplet size and velocity of the spray, respectively. Also spatial velocity distribution of the spray droplet was measured by use of the particle image velocity system. Experimental results show that high pressure gasoline injector shapes the hollow-cone spray, and produce the upward ring shaped vortex on the spray surface region. This upward ring shaped vortex promotes the secondary atomization of fuel droplets and contributes to a uniform distribution of fuel droplets. Most of fuel droplets are distributed under 31$\mu m$ of the mean droplet size (SMD) and the frequency distribution of the droplet size under 25$\mu m$ is over 95% at 7 MPa of injection pressure. According to the experimental results of PIV system, the flow patterns of the droplets velocity distribution in spray region are in good agreement with the spray macroscopic behaviors obtained from the visualization investigation.